The invention relates to an apparatus for treating disorders of biological tissues with light of selected optical parameters. The invention also relates to methods for stimulating healing of disorders of biological tissue with light having selected optical parameters and to methods of stimulating healing of lesions using such light.
Curing with light was known and used in medicine in ancient times. Red or ultraviolet light was successfully used in the 19th century for the treatment of pockmarks and lupus vulgaris by Danish physician, N. R. Finsen, the father of contemporary phototherapy.
Biological phenomena induced by ultraviolet light have been intensively investigated in photobiology and photomedicine for several decades. Ultraviolet light as a phototherapy for some dermatological diseases (mainly psoriasis) has been used since the early twenties. However, ultraviolet light is an ionizing radiation, and therefore has a damaging potential for biomolecules and has to be used in photomedicine with certain precautions.
Biological and healing phenomena induced by optical wavelength (visible) and infrared (invisible) light have been intensively investigated in the last decade. Electromagnetic waves with optical (visible light) and near infrared (invisible irradiation) wavelengths (xcex=400-2,000 nm) provide non-ionizing radiation and have been used in vivo, in vitro and in clinical studies, as such radiation does not induce mutagenic or carcinogenic effects.
Lasers, specific light sources which provide narrow-band monochromatic, coherent, polarized light with wide range of powers and intensities, have been widely used in medicine. Medical lasers may be subdivided into three groups according to their power and ability to produce heat: hot lasers, which are used in surgery; mid power lasers which are used in photodynamic therapy for cancer treatment or in dermatology to treat telangiectasia, port-wine stains, etc.; and low energy (or low intensity, cold or low level) lasers which deliver several orders of magnitude less energy to the tissue than surgical lasers. They produce very little heat in biological tissue or no heat at all.
Low energy lasers have been used in dermatology, traumatology and some other areas to enhance healing phenomena in the body (Mester et al., Lasers Surg. Med. 5:31-39, 1985; Trelles et al., Lasers Surg. Med. 7:36-45, 1987; Ohshiro T., Laser Therapy: Practical Applications, (Ed. T. Ohshiro), John Wiley, Chichester, 1991). The most frequently used terms for this area of physiotherapy are low Energy Laser Therapy (LELT), Low reactive Level Laser Therapy (LLLT), or Laser Therapy. The first successes of LELT were demonstrated in the treatment of chronic ulcers and persistent wounds of different etiology (Mester et al., Lasers Surg. Med. 5:31-39, 1985).
Anecdotal case studies have suggested that LELT is beneficial for a number of dermatological and musculoskeletal conditions. However, LELT has failed to provide good results in well-controlled randomized double-blind studies designed in accordance with rigorous North-American standards (Gogia and Marquez, Ostomy/Wound Management, 38:38-41, 1992; Lundeberg and Malm, Ann. Plast. Surg., 27:53).
Coherence and polarization are the main features which differentiate laser light from regular monochromatic light. Many photoinduced phenomena in cell cultures and biotissue are reported to be induced by noncoherent, nonpolarized monochromatic light (Karu, Health Physics, 56:691-704, 1989 and Karu, IEEE J. of Quantum Electronics, QE23:1703-1717, 1987).
Laser beams lose coherence and polarization because of scattering very quickly after entering tissue and thus deeper tissue layers xe2x80x9cdo not distinguishxe2x80x9d laser from non-laser light.
Low energy photon therapy (LEPT), also known as low energy, low level, low intensity laser therapy, photobiomodulation, is the area of photomedicine where the ability of monochromatic light to alter cellular function and enhance healing non-destructively is a basis for the treatment of dermatological, musculosketal, soft tissue and neurological conditions.
Low energy photons with wavelengths in the range of 400nm-2,000 nm have energies much less than ultraviolet photons, and therefore, low energy photons do not have damaging potential for biomolecules as ionizing radiation photons have.
The area of LEPT research is controversial and has produced very variable results, especially in clinical studies. Almost every mammalian cell may be photosensitive, e.g. could respond to monochromatic light irradiation by changes in metabolism, reproduction rate or functional activity. Monochromatic light photons are thought to be absorbed by some biological molecules, primary photoacceptors, presumably enzymes, which change their biochemical activity. If enough molecules are affected by photons, this may trigger (accelerate) a complex cascade of chemical reactions to cause changes in cell metabolism. Light photons may just be a trigger for cellular metabolism regulation. This explains why low energies are adequate for these so called xe2x80x9cphotobiomodulationxe2x80x9d) phenomena. However, it is difficult to induce and observe these phenomena both in vivo and in vitro using the same optical parameters. Specific optical parameters are required to induce different photobiomodulation phenomena (Karu, Health Physics, 56:691-704, 1989; Karu, IEEE J. of Quantum Electronics, QE23:1703-1717, 1987). The range of optical parameters where xe2x80x9cphotobiomodulationxe2x80x9d phenomena are observed may be quite narrow. The specificity and narrowness of the optical parameters required for xe2x80x9cphotobiostimulationxe2x80x9d in LEPT therapy distinguishes LEPT therapy from the photodestruction phenomena induced by hot and mid power lasers (e.g. in surgery and PDT).
Devices for stimulating biological tissue using low energy light are disclosed for example in U.S. Pat. No. 4,930,504 to Diamantopoulos et al. and U.S. Pat. No. 4,686,986 to Fenyo et al., U.S. Pat. No. 4,535,784 to Rohlicek describes an apparatus for stimulating acupuncture points using light radiation. U.S. Pat. No. 4,672,969 to Dew describes a method and apparatus for closing wounds using a laser tuned to a wavelength of 1.33 xcexcm to produce thermal heating of the tissue to denature the protein.
To meet the changing requirements for optical parameters for different experimental and clinical applications, there is a need for an optical system for xe2x80x9cphotobiomodulationxe2x80x9d having flexible parameters, adjustable for particular applications. In particular, there is a need for an apparatus capable of treating a range of biological disorders by reliably providing light to the affected three dimensional biological tissue, which light has the optical parameters necessary for inducing the appropriate photobiomodulation for the particular disorder and tissue to be treated. There is also a need for a method for reliably providing light having such parameters to a biological tissue having a disorder in order to effect healing.
The present inventors have determined that for each disorder of biological tissue there is a set of optical parameters which constitute the optimal protocol for treating the disorder by LEPT. The optimal protocol depends on a range of factors such as the type of tissue affected, the disorder, the stage of tissue healing (acute, subacute, tissue regeneration stage) and the size and three dimensional placement of the affected area. The optical parameters which make up the protocol include optical power, dose, intensity, wavelength, bandwidth, beam diameter and divergence, frequency and pulse duration. The present inventors have also determined that these protocols may be developed, stored, selected, retrieved from a microprocessor and utilized to provide optimal LEPT treatment for a range of biological disorders efficiently and reliably.
The present invention thus provides an apparatus for treating a disorder of a biological tissue in a mammal by stimulating the biological tissue with light having selected optical parameters. The apparatus comprises a power source for providing power to a central microprocessor; a central microprocessor having stored optical parameter protocols suitable for treating a range of disorders of biological tissue and means for selecting one or more stored optical parameter protocols for the disorder to be treated; including at least one wireless optical probe, having a microprocessor in communication with the central microprocessor, to receive the selected optical parameter protocol and having at least one probe containing an optical source(s) for generating a beam(s) of light having the selected optical parameter protocol and for directing the beam of light to the biological tissue to be treated; and communication means for transmitting the optical parameter protocol from the central microprocessor to the probes, or remotely via telephone and satellite links to any location around the world or outer space.
In an embodiment, the beam of light having the selected optical parameter protocol is substantially monochromatic and has a wavelength of from 400 to 2,000 nm and preferably has a wavelength in the range of from 500 to 2,000 nm, more preferably from 600 to 1,100 nm. In particular, embodiments, preferred ranges include from 360 to 440 nm, from 630 to 700 nm, from 740-760 nm, or from 800-1,100 nm. The optical source may be, for example a laser, laser diode, superluminous or light emitting diode. In an embodiment, the optical source is in pulsed mode with an operating frequency in a range of from 0 to 200 Hz and 1,000-10,000 Hz for short pulses. In a further embodiment, the optical parameters are optical power, dose and intensity, frequency, modulation frequency and phase of stimulation.
The wireless communication means may be acoustic, magnetic or optical.
In a still further embodiment, the apparatus further comprises means for monitoring the condition of the mammal and providing feedback to the central microprocessor to adjust the selected optical parameter protocol based on the condition of the mammal. The means for monitoring the condition of the mammal may be for example EEG (electroencefalography), EMG (electromyography), ECG (electrocardiography), CL (chemoluminescence) or a respirator, or a combination thereof.
In a further embodiment the apparatus comprised and utilized means to modulate treatment optical parameters by endogenous (such as respiratory, ECG, EEG, etc.) frequencies and to provide on-line feedback for selection of stimulation phase in respect to any endogenous rhythm phases.
Another aspect of the invention relates to a method for stimulating healing of a disorder of a biological tissue in a mammal by stimulating the biological tissue with light having selected optical parameters provided by a central microprocessor having stored optical parameter protocols suitable for treating a range of disorders of biological tissue; selecting one or more stored optical parameter protocols for the disorder to be treated; generating a beam of light having the selected optical parameter protocol and directing the beam of light to the biological tissue to be treated.
In an embodiment, the invention provides a method of stimulating healing of a lesion in a mammal, comprising: irradiating the lesion with a substantially monochromatic beam of light having predetermined optical parameters, wherein the predetermined optical parameters include a dose of from 0.2 to 10 J/cm2, an intensity of from 0.2 to 5,000 mW/cm2 and a wavelength of from 400 to 2,000 nm.
In a particular embodiment of the method, the lesion is a chronic ulcer or wound and the selected optical parameters include a dose of from 0.2 to 1.0 J/cm2, an intensity of from 0.2 to 10 mW/cm2 and a wavelength of from 600 to 700 nm. In another embodiment of the method, the lesion is an acute ulcer or wound and the selected optical parameters include a dose of from 2.0 to 5.0 J/cm2, an intensity of from 10.0 to 30 mW/cm2 and a wavelength of from 600 to 700 nm. In yet another embodiment, the lesion is an infected wound and the selected optical parameters include a dose of from 3.0 to 7.0 J/cm2, an intensity of from 50.0 to 80 mW/cm2 and a wavelength of from 600 to 700 nm.
Other objects, features and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples while indicating preferred embodiments of the invention are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.